JPH0332277A - Method and device for compressing digital signal group - Google Patents

Abstract

PURPOSE:To compress an original digital signal group, whose values are changed in the direction of one measured value, to a compressed digital signal group to be changed corresponding to the above mentioned change with satisfactory response by making the length of the measured value direction between respective compressing blocks unequal in the range of a prescribed length. CONSTITUTION:A digital signal group compressor 11 is equipped with a change degree calculating means 12 to calculate the change degree for the value of the original digital signal group, whose values are changed in the direction of one measured value, in the measured value direction, namely, to calculate the change degree of picture data, which are composed of gradation values for the density of a picture 1, in an X direction. A compressing block length determining means 13 is provided to calculate the length of the compressing block in the measured value direction, namely, the length of the X direction corresponding to the change degree calculated by this change degree calculating means 1 2 for the picture data. The range of the picture data in all the scanning direction is divided into the unequal compressing blocks with the various length of the blocks, namely, with the various lengths in the X direction and by using the respective compressing blocks, the original digital signal group is respectively converted into one compressed digital signal. Thus, the compressed digital signal group, for which the original digital signal group is efficiently compressed, can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention compresses a group of original digital signals whose values change with respect to one measurement direction into a group of reduced digital signals whose number of days of communication is J: less than 1]. The present invention relates to a method and apparatus for compressing digital signals gnYIxt.

(Prior art) In general, it is common to convert an arbitrary amount of change into a group of original digital signals whose values change in one measurement direction, and to improve the efficiency (in order to improve V) of further utilizing this group of original digital signals. To,
Although the tendency of value changes corresponds to the original digital signal group, the number of signals is compressed and converted into a compressed digital signal group that is smaller than the number of signals of the original digital Buddhist symbol group.

As an example of compressing such a digital signal group, there is a case where arbitrary images 1 are printed on a sheet 3 as a reproduced image 1a as shown in FIG. 9, for example.

To explain further, in Fig. 9, both characters (brass 1 and character 2) shown in the leftmost part are edited and sent to pudding 1 as reproduced image 1a and reproduced character 2a on river paper 3 so as to be accepted in the rightmost part. , one character 2 is converted into digital digitized data by a literary data input device 4 such as a guitar board, and is input as character data to a post-processor 6. The other image 1 is an image character (・The image data is read as image data by the image data input unit 5 such as No. The original digital signal 8 is made up of a set of digital signals measured for each unit pixel.This original digital signal is used as it is for printing image 1, but the amount of information is too large, 6 and the CPU of the printer 7, etc., they must be made to have higher performance than necessary, and they become expensive.

Therefore, a compressed digital signal that changes according to changes in the original digital signal and has a small number of signals has been created, and this compressed digital signal is used to create a compressed digital signal that changes according to changes in the original digital signal. -Editing the image 1 and character 2 by 6 J: It's turning into a sea urchin.

The print data created by the combination coater 6 is sent to the printer 7, and the printer 7 prints the print data on the paper 3 based on the received print data.
ijij image 1aJ> and 1/1: intersection 2a is printed 1-.

(Problem to be solved by the invention) However, the conventional original digital communication; The method of compressing Y (1 degree, that is, the image data person) had the problem of first-order compression. The reading of the shading of image 1 by No. 5 is carried out by repeating the measurement in the X direction while scanning image 1 in X111J as shown in FIG.

Figure 10 shows l! lii statue 1
It shows image data consisting of the intensity of the image 1 along the scanning line, which is obtained by scanning the image in the X direction. σ) 1Uji fullI data is
The gradation of the furniture (
Let fi be a digital signal value, and these digital values (i
;'I display the i value as a line graph, and
This is a type of original digital signal group whose value changes in the 7'J direction. When compressing this image data, as shown in Figure 10, the entire scanning range of image 1 in the The original digital signal iY is compressed into one compressed digital signal 8.

However, as in the image data shown in FIG. 10, the original digital signal group often includes a high frequency component element A region whose value changes rapidly and a low frequency component region whose value changes slowly. In order to compress the high frequency component so that it changes responsively in response to the change, it is necessary to know the length in the Illll measurement direction, that is, the length in the X direction, of the shoreline section to be equally divided.

However, if the length of the J1-reduced section in the X direction is made smaller, more compressed digital signals than necessary will be created due to J3 in the low frequency component region, which will contain redundant data as a whole and reduce the compression efficiency. This results in a bad result and ends up putting a heavy burden on the subsequent 8 seconds of control processing on the host computer 96 and printer 7. For this reason, in the conventional method described above, in I3, the average division number of the 0.11th whole scan, that is, the length in the measurement direction of the compression section, is determined to be quite appropriate IK+. I couldn't do it/,,: ,.

The present invention provides gr h'-(e of L made at these points)
In order to convert the original digital signal group whose value changes in one measurement direction into a compressed digital signal group whose value changes responsively to the change, and to achieve efficiency j:<compression in a small compression interval. The object of the present invention is to provide a method and apparatus for compressing digital signals.

(Means for Solving the Problems) In order to achieve the above object, the digital signal group compression method of the present invention converts the original digital signal group in which (lf+ changes) into 111i measurements (Iff In the digital signal g8Y compression method, which uses compressed sections divided into a plurality of compression sections in the h direction, the length in the measured direction for the first compression period of each month is within a predetermined vertical range. Characterize 1] as unequal.

In addition, in order to achieve the above-mentioned objective 1, the digital Shinkyu group compression device of Mokimitsu 1su is capable of converting changes in the value of the original digital signal flY in the measurement direction, the value of which changes with respect to one measurement direction. and a compression section length determining means for determining the length of the compression section in the ft1 direction according to the degree of change of the original digital signal group obtained by the change degree calculation means. It is characterized by being formed in this way.

[For production]

According to the present invention, by operating the apparatus of the present invention in accordance with the method of the present invention, it is possible to obtain a 1-1 reduced digital signal R, which is an efficient shoreline of the original digital signal H41y.

In other words, the degree of change calculation means calculates the degree of change in the value of the original digital signal in the measurement direction, and the compression section length determining means determines the quality of the compression section according to this degree of change. As a result, each compressed digital signal is created based on each single line section whose measured value direction length is uneven within a predetermined length range, and compression that responds well to changes in the values of the original digital Shingan Group. An efficient "reduced digital signal group" can be obtained.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 8.

In this embodiment, as the original digital signal BY, image data consisting of 211 degrees of lightness of image 1, as in the conventional case, is used as an illusion, as shown in FIGS. 1 and 2. 1 FIG. 1 schematically shows the digital signal group reduction system 11 of the present invention.

Digital Shinji group compression device of this embodiment? ¥111, 1
Calculate the degree of change in the value in the measurement direction of the original digital signal group whose value changes in two measurement directions, that is, the degree of change in X/11 of the image data consisting of the m-degree gradation scale of image 1. Change degree calculation means 12 and this change degree calculation means 12
According to the degree of change in the image shape that has been removed by Using the determined compression ratio 18, the original digital signal is compressed into one compressed digital signal according to a predetermined method (compression means 11). .

Next, the operation of this embodiment will be explained.

In this embodiment, as shown in FIG. The three groups of original digital signals are each converted into one compressed digital signal using a compression interval. .

This operation will be explained with reference to the outline chart in Fig. 4. When the compression processing operation starts from star 1, the image data input device
Detection scanning of the temperature in a certain X direction of image 1 is performed, and image data reading, that is, reading of the original digital image group is performed. Next, as shown in step 5-r12, a compression interval is set by the change degree '/rA calculating means 12 and the compression interval length determining means 13. ? I-
The degree of change calculation means 12 calculates the degree of change in the values of the original digital event H group, and the length of the compression interval is determined at stage f1.
3, the length of the compression section is determined according to the degree of change.

Next, in step 5T13, the signal compression means 14 creates a compressed digital signal group according to a predetermined method j (using the compression section).

There are various methods for setting the compression section in sub 5l-12, but as shown in the image data shown in FIG. It is better to shorten the length of the compression interval in the part where the degree of change in value is severe, and to lengthen the length of the compression interval in the part where the change in value + a is gradual. [Response to] well-corresponding compressed digital signal]
1, which can jj the liver, also step S-1-
12 (J3-1) In order to concretely set the reduced section (indicated by a black circle on the X axis in Figure 3), each J3-1
By determining the starting and ending points of the section ii, it is possible to carry out the process smoothly and appropriately.

This selection of interval points is shown, for example in FIG.
It is preferable that the change degree calculating means 12 i15 J: and the compression section length determining means 13 perform the calculation according to -t-.

That is, in step 5T21, a plurality of X coordinates of the pixel Da in the image data of FIG. 3 where the degree of change in value is large is selected as interval point candidates. Next, in step 5T22, the plurality of interval point candidate sets selected as described above are narrowed down to a predetermined number of interval point candidates. Next, in step 5135J3, the candidate points are narrowed down to those whose interval points are separated by a predetermined minimum number of pixels or more as described above. Next, step 5l-
In step 24, a number of new interval point candidates corresponding to the number reduced by the narrowing down in step 5T23 is added to obtain the predetermined number of interval point candidates. Next, in step 51-25, section points are added by remote determination. That is, if each interval of the predetermined number of interval point candidates determined as described above is separated by a predetermined maximum number of pixels or more, the interval point candidates are divided evenly into within the maximum number of pixels. is added, and a compressed interval is determined using all these interval point candidates as interval points.

An example of further embodying 71''-17-1 in FIG. 5 is coach t/-1 in FIG.

To further explain this FIG. 6, step 5T31
Select multiple interval point candidates in step 1. This selection selects locations where the degree of change in image data is large, and the selection methods include, for example, the following (1) and (2).
Nojoi? It is preferable to select j pixels that satisfy 1.

Now, let the tone value of one pixel data shown in FIG. )−g(i), then (1) D −D<0 (+−1) (i) (2) max(l D(ii) l , l
D(H)l ) >C However, C is a constant (default fin
) where both conditions are not met.

The conditions <1) and (2) mean that the digital signal of the pixel portion with the The condition is that the magnitude of the change exceeds the degree of change in which the product of the absolute values of each amount of change is greater than or equal to a predetermined number C.

Next, in step 5l-32, for each section point candidate selected in step 5T31, the operation n(llj of the following formula %) () is assigned in order from the largest one.In this case, If there are multiple interval point candidates with the same value and it is necessary to select one from among them, for example,
The selections are made in order of decreasing ordinal value.

Next, in step 5T33, a predetermined number (for example, 30>) of upper section points are selected from the set of section point candidates.

Next, in the smartphone 5T34, a neighborhood condition is determined as to whether or not the interval between the 30 selected section point candidates falls within a predetermined minimum number of pixels. If the section point candidate is located nearby, it is determined as YES and the process proceeds to step 51.
The process proceeds to step 35, and if there is no one nearby, the determination is No and the process proceeds to step 2 SF38, which will be described later. 1. Next, in step S l' 35, one of the two interval point candidates placed near each other is deleted, and the other is left as an interval point candidate. In this case, now x/! ', Assuming that the interval point candidates of points i and j are neighbors, 0 fi−11”(+) and [)(j−
o ” D (J), keep the larger one and delete the other.

Next, in step S-36, it is determined whether the total number of section point candidates selected up to the current I' is the predetermined number (30 in this embodiment) determined in step 5T33,
In the case of YES, the process proceeds to step 5T38, which will be described later. In the case of No, the process proceeds to step S-1-3.

In this step 5137, the predetermined number (30)
Step 5T
32 In the same way, select and add from the top, step 5
Return to T36.

These steps STd'i and ST3□ are repeated until the determination in step ST3□ is YES.

Next, in step S38, it is determined whether each interval between the interval points obtained as described above is equal to or less than a predetermined maximum number of pixels. It is determined whether or not it is less than or equal to 20i!!Ii elements. If Y[S, the section pre-selection operation is completed, and if NO, the process proceeds to Stella 1S, 9.

In this step 51139, the interval between the interval points is 2.
Section points are added to evenly divide the section from 0 pixels to 20 pixels or less so that the section length is at most 20 pixels or less. In this division, the compression efficiency is increased by defining the number of additional interval points as the minimum necessary number. This lu
The pre-section selection operation ends with the addition of the laI point.

By determining the interval points in this manner, as shown in FIG. 3, the compressed interval between each interval point is determined. This compression section is set such that the section length is short in the high frequency component region and long in the low frequency component region.

Thereafter, in step 5113 shown in FIG. 4, a compressed 5'r digital signal 4 is determined using each compression section, and as a whole, a group of compressed digital signals in one scanning direction is determined.

By repeating this compression processing operation for all pixels in the X direction, image data for the entire image 1 is created.

The compressed digital bow group obtained in this way is sent to the boss 1 to the computer 6, and the character 2 sent to the host 1 to the computer 6 through the character input device 4.
It is used to create a print signal that performs &i collection with 0 character data, etc., and is reproduced on the paper 3 by the printer 7 l! I image 1a
It is served with pudding.

The image quality of the reproduced image @ 1a is the original image 1
The image quality is almost the same as that of .

This means that the degree of change G of the digital signal group pressure line device 11 is within a predetermined length range (in this embodiment, 20
iii! Non-uniform compression 1 with interval length (within l elements)
Between g, the reproduced compressed digital signal group created by the signal compression f stage 1/I is connected so as to change smoothly in the This is because the same specialty changes. Also, is the compressed digital signal @ group the original digital signal? Compared to lY, the amount of information, that is, the amount of data, is compressed and reduced by one person.
The load placed on the boss 1 to combi coater 6 and link 7 is reduced, and high-speed data processing is possible.
You can also

Next, the same original digital signal 1! (2) was obtained by performing 98 compression techniques using the method of this embodiment and the conventional method,
The reproduced compressed digital signal groups in which each compressed digital Shingan group J3 and each compressed digital Ikuyoku are connected so as to change smoothly in the X direction are shown in FIGS. 7 and 8 ("Compare. The figure shows the results obtained by the method of this example.
The image data to be compressed (shown in solid lines in both figures) has 256 pixels (11
2), and the density gradation of image 1 is expressed as a digital g value for each pixel in the entire scanning direction range.

In the method of this embodiment, -( is j shown in FIG. 7,
, the entire scanning direction range is unevenly divided into a predetermined length range (with 49 compressed sections with different section lengths (section points are indicated by black circles or white circles on the X-axis - H). Then, the j1 compressed digital signal is created using the IT compressed interval7.This one compressed interval must be kept short in the high frequency component region, and if the fluctuation of the gradation value is always large. , it is possible that the interval length is 0''. (In 118 where the interval length is "o", there are overlapping interval points on the same -X coordinate (measured force direction). ) In this example, as shown in Fig. 7, 1211 points of 9 xen 1 sections exist overlappingly (1 point indicated by a white circle), so all 49 compressed sections (-673- Relationship with famous cases involving E8Y compression method and equipment correction Patent applicant (AO9) Alps Electric Co., Ltd.

Claims (1)

[Claims] 1) A digital signal group compression method in which an original digital signal group whose value changes with respect to one measurement direction is compressed using compression sections divided into a plurality of compression sections in the measurement direction, A digital signal group compression method characterized in that the lengths of the compression sections in the measurement direction are made uneven within a predetermined length range. 2) change degree calculation means for calculating the change degree of the value in the measurement direction of the original digital signal group whose value changes with respect to one measurement direction; and A digital signal group compression apparatus comprising compression section length determining means for determining the length of the compression section in the measurement direction according to the degree of change.